Aggregate gradation
The distribution of particle sizes in the sand and stone. Good gradation packs particles efficiently so less paste is needed to fill the gaps.
What does aggregate gradation mean?
A well-graded aggregate has a continuous spread of sizes, letting small particles nest between large ones. Gap-graded aggregate leaves voids that must be filled with paste, raising cost, shrinkage, and cracking risk. Producers manage gradation by blending stockpiles, and a change in gradation is a frequent hidden cause of a mix that suddenly finishes differently.
In practice
When a familiar mix starts behaving strangely with no spec change, gradation drift at the pit is one of the first things a producer checks.